zstan: Same result what. I just worded it differently.

Reach = Guide Number * square root of (current ISO/ISO 100) / F number

So reach = 58 meters * square root of (ISO400/ISO100) / F4
= 58 meters * square root of 4 / F4
= 58 meters * 2 / 4
= 29 meters

Nice ones on #2 and #3!

my lens suddenly making loud noise if i turn on the camera.i think the autofocus is broken.im using a200.how much to repair it.plz help me.

Gear stripped lenses are expensive to repair??

Same with me...so annoying...can I claim the warranty for this problem?

i think alot of lenses still not in alpha line up..
and again if they make one.. got a slight enhancement..
but still can be used right.. why worry much..

im using standard kit lens.how much to repair the problem?

Yes, is an external flash.
can feel loosen after slot in the external flash.
Flash can move ( longga ) 

zstan : I don't think it's reverse engineered lar... I would think that the mount information is easily available from the manufacturers like Sony or Canon or Nikon. It does not stand to logic that they will stop third party lens maker from making lenses for their mounts.

either u missunderstood, or ur uncle outside misgear or misguide by 'seller/promoter'

it happened about 24-27 years ago, where, when the first AF firstly introduced. canon has to re-engineer the whole mount causing old lenses are unable to be used on the new body with AF, nikon stays with the same mount with minor modification, hence, during that era, canon loses a lot 'fan' and all jump to nikon. to make story short or being pass through 50 people, it becomes, "old lens cant use on new camera" =.=, partly, all u need is "adapter, or, perhaps u only can MF" thats all. BUT its RARE to find a >25 year old lens, mostly will get fungus because that era, drybox arent popular.
(maybe i was wrong and misunderstood ur statement)
and, today people ARE SMART, they wont build something to destroy old market(or maybe they will, like intel socket, LOL)... future camera are "backward compatible" meaning it WILL support older
chips" (like how we have 8 pins on the alphas, but still able to use 15 year old KM50mm with 5 pins)

*btw, sony have a minor share of Tamron, and tamron have given/share exclusive lens design to sony and some of sony lens are tamron design just some cosmetic changes. safe to say, tamron lens are pretty optimized for alphas

btw, i think the word u are looking for is backward compatibility, not reverse engineered. LOL, coz they sound 'back-wards' LOL.

lens backward engineered mean, they make lens only make mount/body. or it could mean, they try redesign similiar design of VR/IS or HSM/SSM from the existing design, which has no issue wor.

also, there is a STANDARD they follow on the each Mount. so, wont differ a lot.

It will all depend on whether I can save up money or not end of this month. If I cant meaning that I will have to send it to garage sales. Hehehhe.
Problem with it is I have a rather tight budget on getting a camera and I need to save up for something else. Im still thinking tho but I will make a decisions later this year.

Not really in a rush to shoot. Just that I need to save up on something else.

I wanted to sell off to fund for my flight ticket to Japan. But if I were to sell off my gears, I wont have anything to use to shoot in Japan tho. Heheh.

Cant really do part times now cause my working time is slightly changing. Sometimes I even have to work on sat/sun.

My trip there would be only for a certain reason actually. Cause Im going alone.

Well not exactly know when yet but hopefully this year.

Well I have to go before April next year tho. Thats the due date. I think I should think about this cause I really dont wanna sell off my gears but for some reasons I have to. Hehehe~

Was planning to go on Jan or Feb for winter or April for sakura tho. Hhahaha.